.clock {
  display: flex;
  width: 420px;
}
.clock .divider {
  font-size: 66px;
  line-height: 102px;
  font-style: normal;
}
.clock .flip {
  position: relative;
  width: 60px;
  height: 100px;
  margin: 2px;
  font-size: 66px;
  line-height: 100px;
  text-align: center;
  background: white;
  border: 1px solid black;
  border-radius: 10px;
  box-shadow: 0 0 6px rgba(0, 0, 0, 0.5);
}
.clock .flip .digital::before, .clock .flip .digital::after {
  position: absolute;
  content: attr(data-number);
  left: 0;
  right: 0;
  color: white;
  background: black;
  overflow: hidden;
  -webkit-perspective: 160px;
          perspective: 160px;
}
.clock .flip .digital::before {
  top: 0;
  bottom: 50%;
  border-radius: 10px 10px 0 0;
}
.clock .flip .digital::after {
  top: 50%;
  bottom: 0;
  line-height: 0;
  border-radius: 0 0 10px 10px;
}
.clock .flip .back::before,
.clock .flip .front::after {
  z-index: 1;
}
.clock .flip .back::after {
  z-index: 2;
}
.clock .flip .front::before {
  z-index: 3;
}
.clock .flip .back::after {
  -webkit-transform-origin: center top;
          transform-origin: center top;
  -webkit-transform: rotateX(0.5turn);
          transform: rotateX(0.5turn);
}
.clock .flip.running .front::before {
  -webkit-transform-origin: center bottom;
          transform-origin: center bottom;
  -webkit-animation: frontFlipDown 0.6s ease-in-out;
          animation: frontFlipDown 0.6s ease-in-out;
  box-shadow: 0 -2px 6px rgba(255, 255, 255, 0.3);
  -webkit-backface-visibility: hidden;
          backface-visibility: hidden;
}
.clock .flip.running .back::after {
  -webkit-animation: backFlipDown 0.6s ease-in-out;
          animation: backFlipDown 0.6s ease-in-out;
}

@-webkit-keyframes frontFlipDown {
  to {
    -webkit-transform: rotateX(0.5turn);
            transform: rotateX(0.5turn);
  }
}

@keyframes frontFlipDown {
  to {
    -webkit-transform: rotateX(0.5turn);
            transform: rotateX(0.5turn);
  }
}
@-webkit-keyframes backFlipDown {
  to {
    -webkit-transform: rotateX(0);
            transform: rotateX(0);
  }
}
@keyframes backFlipDown {
  to {
    -webkit-transform: rotateX(0);
            transform: rotateX(0);
  }
}